Answering part of my own question here using the rawhide test instance:
$ pkg-config --libs glew -lGLEW -lGLU -lGL
Minimal CMake test config:
$ cmake . -- GLEW_LIBRARIES: /usr/lib64/libGLEW.so -- Configuring done -- Generating done
It looks like -lGLU is being picked up somewhere else in the build but not -lGL...
Thanks, Richard